Embryonic development and homologous, analogous and vestigial organs.

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Transcript of Embryonic development and homologous, analogous and vestigial organs.

Embryonic evolution and homologous, analogous and vestigial organs. The experiments that proved the theory of evolution. Embryonic development Some embryos from different species are similar, which shows that there is a clear evolutionary relationship between them. According to studies that have been done to embryos of different species such as fishes, birds, mammals and humans, and according to Darwinism, they show that these species are descended from common ancestors, which were similar to fishes.At the first stage we can see that the more visible similarities are that they have tails, and that the shapes of their heads are similar too. Also I don’t know if is a coincidence but all of them are like in a “J” form. But when they grow the similarities are among a smaller number of species.The similarities between embryos are greater and last for more time in groups of organisms that are closely related to each other. ++ Homologous Organs Homologous organs are those that have the same or similar internal structure and in spite of this they have different functions.They are proof of divergent evolution or adaptive radiation, in other words these organs prove that some species come from a common ancestor.An example is the wings of a bird and the arms of a human.Classifications based on homologous organs are natural. Divergent: moving away from each other Divergent: moving away from each other. Adaptive radiation: diversification of a species into several different forms. Analogous Organs Analogous organs are those that have the same function but a different structure and image. An example is the wings of insects and birds.They are proof of convergent evolution, in other words that some species come from different species, but because of their conditions, they have needed to develop similar adaptations.According to this, we should classify insects and birds together, but the classifications based in analogous organs are artificial. Vestigial Organs A vestigial organ is when the function of this organ has been lost during the evolution. An example is the wisdom tooth, the wings of the now flightless kiwi bird or the appendix. THE END